Immunobiology of the xenograft response: xenograft rejection in immunodeficient animals.

These studies provide insight into the immunobiology of xenograft rejection. They suggest that xenograft rejection involves T-cell phenomena, although the ability of the nude rat (functionally known to be T-cell deficient) to reject the vascularized xenograft normally is striking and clearly indicates a need for future studies of this phenomenon. These studies strongly suggest a role for NK and K cell-type activity in xenograft rejection, although they also indicate this immune function is only an ancillary one and that xenograft rejection will eventually occur despite deficiencies in these systems. These studies are most provocative in showing a failure of efficiency of skin graft rejection in the purest model of B-cell deficiency, the XID model. Since these results are obtained with the so-called secondarily vascularized xenograft (skin grafts) it is not possible to exclude the role of B-cell and B-cell-associated phenomena in vascularized organ grafts without further studies.